The invention relates to the field of the remote control of actuators and in particular, the wireless control of actuators used in the amenities and security of buildings, in particular for lighting, operating closures, solar protection, ventilation and air-conditioning systems etc.
In the current design of such systems, such actuators and/or associated sensors are controlled by control units or control points capable of communicating by reception but also by transmission via a bidirectional link, typically a radio frequency link. The actuators and or sensors and the control units can therefore be qualified generically as bidirectional objects. The actuators and or sensors are often installed in the parts of the building which are difficult to access for the installer and even more difficult for the user.
The control points are unidirectional or bidirectional, roving or fixed. Very often a fixed control point is itself battery powered, which avoids wiring. When a control point is equipped with a transceiver, the reception function can only be activated on command or intermittently in order to limit consumption.
A pairing procedure makes it possible to associate a common identifier with a pair formed of an actuator and a control point. The sharing of a common identifier then makes it possible for the actuator to recognize the controls originating from the control point, in command to respond to it. The pairing procedure can be repeated so as to control several actuators from one control point or also so that one actuator responds to several control points. Depending on the pairing procedure, the identifier is transmitted from the control unit of the actuator to the control point, which records it, or conversely from the control point to the control unit of the actuator, which records it. Pairing solutions are, for example, described in U.S. Pat. No. 4,529,980 or U.S. Pat. No. 5,148,159 or also in French patent applications filed by the Applicant under serial numbers 01 09369 of Jul. 13, 2001 and 01 16709 of Dec. 21, 2001.
When it is a question not only of amenity but also security, a problem arises if a control point is lost or stolen. In fact, a stolen actuator can be used remotely, for example, to deactivate an alarm or also to open a door or a rolling shutter.
U.S. Pat. No. Re 36,703 presents a solution to such a problem. It relates to a control unit of an actuator for garage doors which is able to learn several identifiers, all different, belonging to different remote control transmitters. A software or mechanical pointer allows a new memory location to be assigned to a new transmitter. In the case of loss (or stealing) of one of the transmitters, the corresponding memory location is pointed to in order to enter the code of the replacement transmitter there. The old transmitter thus becomes invalid in that its identifier is overwritten by the writing of a new identifier. This solution requires that a table of the relationships between transmitters and memory locations assigned to each transmitter be kept in a safe place.
EP-A-0,688,929 describes learning mechanisms in code hopping systems, with an analog solution. This document states that it may be necessary to exclude a transmitter from the system. The solution proposed is as follows: an encoder is excluded by suppressing the corresponding codes in the decoder—in other words simply separating the encoder and the decoder.
Another solution consists in starting a pairing procedure of all of the actuators again. The French patent application filed on Jul. 7, 2001 under Ser. No. 01 09369 thus proposes actuators, in which action on the power supply causes actuation of the programming mode. Another solution consists in resetting an actuator by actuating the phase of a specific wire as disclosed in FR-A-2,808,834. It is understood that such means requires that the pairing procedures be started again completely. To compensate for the loss or disappearance of a command point we are thus required to delete the indentifiers of all of the command points of the installation. Moreover this solution is complex and it is not always possible to implement it, in particular in the case of command points preassigned to actuators in the factory or when the various actuators are not accessible.
In the field of electronic locks it has been proposed to take advantage of the introduction of a new key to eject the code of the preceding one. Such a method is used for example in the documents EP-A-0,171,323 or even earlier U.S. Pat. No. 3,821,704. In a hotel room lock, an electronic key contains a code with two fields A and B. Field A contains the valid access code, field B contains the authorization field. A new key is provided for the next client, this time containing B and C. The first field is used to control the opening if there is identity between the one read on the key and the one recorded in the lock. If there is no identity, the lock compares this first field to the authorization code recorded in the lock. If there is identity, the lock records this code as a valid access code and records the second field of the key as a new authorization code.
EP-A-1,085,481 discloses an installation in which all of the elements of the installation share a site code, unique to the site. The site code is used by the transmitters to encrypt the information transmitted to the receiver. The receiver decrypts the information that it receives from the transmitters, using the site code. It responds to the commands of a transmitter if the information that it receives from this transmitter agrees with the information received previously from the transmitter. The advantage presented in the document is that any programming of the receiver is avoided. However, this document does not mention the problem of loss of a transmitter or deletion of a transmitter; in fact the proposed solution makes the deprogramming of one of the transmitters impossible.
Thus a problem still exists in the case of loss or stealing of a control unit, or more generally when seeking to exclude an object from a group of paired objects.